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epair(4) [minix man page]

EPAIR(4)						   BSD Kernel Interfaces Manual 						  EPAIR(4)

epair -- A pair of virtual back-to-back connected Ethernet interfaces. SYNOPSIS
To compile this driver into the kernel, place the following line in your kernel configuration file: device epair Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5): if_epair_load="YES" DESCRIPTION
The epair is a pair of Ethernet-like software interfaces, which are connected back-to-back with a virtual cross-over cable. Each epair interface pair is created at runtime using interface cloning. This is most easily done with the ifconfig(8) create command or using the cloned_interfaces variable in rc.conf(5). While for cloning you only give either epair or epair<n> the epair pair will be named like epair<n>[ab]. This means the names of the first epair interfaces will be epair0a and epair0b. Like any other Ethernet interface, an epair needs to have a network address. Each epair will be assigned a locally administered address by default, that is only guaranteed to be unique within one network stack. To change the default addresses one may use the SIOCSIFADDR ioctl(2) or ifconfig(8) utility. The basic intend is to provide connectivity between two virtual network stack instances. When connected to a if_bridge(4) one end of the interface pair can also be part of another (virtual) LAN. As with any other Ethernet interface one can configure vlan(4) support on top of it. SEE ALSO
ioctl(2), altq(4), bpf(4), if_bridge(4), vlan(4), loader.conf(5,) rc.conf(5), ifconfig(8) HISTORY
The epair interface first appeared in FreeBSD 8.0. AUTHORS
The epair interface was written by Bjoern A. Zeeb, CK Software GmbH, under sponsorship from the FreeBSD Foundation. BSD
July 26, 2009 BSD

Check Out this Related Man Page

VLAN(4) 						   BSD Kernel Interfaces Manual 						   VLAN(4)

vlan -- IEEE 802.1Q Virtual LAN network device SYNOPSIS
pseudo-device vlan DESCRIPTION
The vlan interface provides support for IEEE 802.1Q Virtual Local Area Networks (VLAN). This supports the trunking of more than one network on a single network interface. This is particularly useful on routers or on hosts which must be connected to many different networks through a single physical interface. To use a vlan interface, the administrator must first create the interface and then specify the VID (VLAN identifier, the first 12 bits from a 16-bit integer which distinguishes each VLAN from any others) and physical interface associated with the VLAN. This can be done by using the ifconfig(8) create, vlan, and vlanif subcommands from a shell command line or script. From within a C program, use the ioctl(2) system call with the SIOCSIFCREATE and SIOCSIFVLAN arguments. To be compatible with other IEEE 802.1Q devices, the vlan interface supports a 1500 byte MTU, which means that the parent interface will have to handle packets that are 4 bytes larger than the original Ethernet standard. Drivers supporting this increased MTU are: - drivers using the DP8390 core (such as ec(4), ne(4), we(4), and possibly others) - bge(4) - bnx(4) - ea(4) - eb(4) - epic(4) - etherip(4) - ex(4) - fxp(4) - gem(4) - hme(4) - le(4) - sip(4) - ste(4) - stge(4) - ti(4) - tl(4) - tlp(4) - vge(4) - vr(4) - wm(4) - xi(4) vlan can be used with devices not supporting the IEEE 802.1Q MTU, but then the MTU of the vlan interface will be 4 bytes too small and will not interoperate properly with other IEEE 802.1Q devices, unless the MTU of the other hosts on the VLAN are also lowered to match. EXAMPLES
The following will create interface vlan0 with VID six, on the Ethernet interface tlp0: ifconfig vlan0 create ifconfig vlan0 vlan 6 vlanif tlp0 After this set up, IP addresses (and/or other protocols) can be assigned to the vlan0 interface. All other hosts on the Ethernet connected to tlp0 which configure a VLAN and use VID six will see all traffic transmitted through vlan0. The same VLAN can be created at system startup time by placing the following in /etc/ifconfig.vlan0: create vlan 6 vlanif tlp0 SEE ALSO
ifconfig(8) HISTORY
The vlan device first appeared in NetBSD 1.5.1, and was derived from a VLAN implementation that appeared in FreeBSD and OpenBSD. BUGS
The vlan interfaces do not currently inherit changes made to the physical interfaces' MTU. BSD
December 16, 2010 BSD
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